There are people (mostly liberal-democrats) who claim.

Factually, Iran WAS at some time in the past prevented from creation of nukes while Joint Comprehensive Plan of Action was in power.

Is the claim that the JCPOA prevented Iran from developing nuclear weapons verifiable?

Because I basically do not trust anyone (Especially the Liberal Democrats). And I also know people who claim that Iran has an undeclared nuclear program, and their claims can even be verified.

If you want to know why I do not trust the Liberal Democrats, because Carter declared during his visit to Iran that Iran is an island of stability and a few weeks later there was a revolution in Iran and Iran and Iraq went to war with each other for eight years. Just for the record.